From reading the code, it doesn't seem like BPopover accepts a target function that returns the element:
https://github.com/bootstrap-vue-next/bootstrap-vue-next/blob/main/packages/bootstrap-vue-next/src/utils/getElement.ts

Nor is target prop reactive. Thus if it depends on a target being mounted and rendered, then the parent component will need to do a v-if="targetExists" on the popover.

Yes, we decided to not include the function target. Didn't see a need for it, since you can just but the same logic in your component.
The target prop is reactive, can you show a case where it didn't work? You can use template ref as a target, dom element, dom id or a dom query string.

Can you shere the code of what you are trying to do so I get a clearer picture why this isn't working for you?

I had opened an issue about it a few months ago, and you directed me to use the new target slot. Works great! Thanks!
#2038